The three piece series of Dalbellos are awesome. The ZS and ZX line and the Kryptons all hold the heel back really well and flex super smooth. Their other normal two piece lines like the Avanti are just a variation on every other boot on the market. I have been in Lange, Alpina, old Dalbellos, Technicas, Nordicas, and Kryptons and the Krpyton slays them all. Just look at the pros who are soliciting sponsors for these boots. Just make sure you don't just get any Dalbello thinking they all fi similarly. Go three-piece and forget about it.